The present invention relates to a battery plate stacker, and more specifically relates to a battery plate stacker including a wire flattener module and a method of operation therefor.
The context for the present invention deals with battery plate stackers. However, prior to discussing the specific operation of a battery plate stacker, it is necessary to first understand the general steps involved in the production of batteries. In its simplest form, a battery comprises a plurality of positive and negative plates stacked in alternating fashion, and having a separator material interspersed between them. The battery plates are retained in a battery container, which also contains electrolytic fluid. The chemical interaction between the electrolytic fluid and the battery plates generates electrical current, which is drawn out through the battery terminals.
For example, U.S. Pat. No. 5,384,217 discloses one process for producing battery plates. This process for making such plates includes an initial step of melting hot lead in a furnace, followed by a step of feeding molten lead alloy to a strip caster. Trim from the caster is recycled to the furnace. The strip is coiled on a winder, and coils of lead alloy strip are stored for later use.
To form a battery grid, the coil is unwound and the free end is fed through an expander that cuts, slits, and stretches a strip of coil to form a mesh-like wire grid. U.S. Pat. Nos. 4,315,356 and 4,291,443 disclose expanders used in the production of wire grids for use in making negative expanded metal battery plates. The expanded strip or wire grid is then pasted by a conventional paster, and fed to a divider where the strip is cut. Plates cut from the strip are next flattened in order to smooth out any uneven regions of battery plate paste. From here, the plates pass on a conveyor through an oven for flash-drying, and are then stacked for later use. Flash-drying is performed using an open gas flame or an oven. After flash drying, the battery plates undergo a chemical treatment, well known to those skilled in the art.
Following chemical treatment of the battery plates, negative expanded metal plates are delivered to a stacker operator. Stacks of the negative expanded metal plates are then manually prepared by loosening the bonding, which results from the chemical set process, between adjacent plates. Next, the plates are inspected for visible damage prior to loading into the battery plate stacker.
Battery plates stackers, such as those manufactured by Tekmax of Oregon, are well known to those skilled in the battery arts. Such battery plate stackers generally include means for feeding the negative and the positive battery plates into the battery plate stacker, an enveloping module for wrapping negative expanded metal battery plates with a separator material, a conveyor for moving the negative and positive battery plates, and a module for stacking the negative and positive plates together.
In general, battery plate stackers are operated as follows. First, negative expanded metal battery plates are placed into the negative plate feeder, while positive battery plates are placed in a separate feeder. Individual negative expanded metal battery plates are separated from their stack and picked up by well known means, such as with a vacuum-type system, for moving the plates onto a carrier. Once on the plate stackers"" carrier, the negative expanded metal battery plates are transferred through the plate stacker to the enveloping module. Here, the negative expanded metal battery plates are enveloped in a separator material. Additionally, a set of meshed wheels seal the separator material around the negative expanded metal battery plate, with the lug side of the plate open. The side of the negative expanded metal battery plate located opposite the lug side is flush against a crease in the separator material. At present, it is common during this crimping process that bent, exposed wires of the negative expanded metal battery plates"" wire grid will pierce the separator material.
Next, separator-enveloped negative expanded metal battery plates exit the enveloping module and enter the stacking module. The stacker module will prepare a series of alternating negative and positive plates. Those skilled in the art understand that a single enveloped negative plate matched with a single positive plate is called a xe2x80x9cchapter,xe2x80x9d while a plurality of stacked chapters is typically referred to as a xe2x80x9cbook.xe2x80x9d
The process of stacking the positive plates onto the negative plates is accomplished with a positive plate feeder that stacks a positive plate onto a separator-enveloped negative expanded metal battery plate as it is conveyed past the positive battery plate feeder. From this point, the book of battery plates are transferred into a cast-on strap machine. The cast-on strap machine will cast a strap to join all negative plate lugs, and a separate strap to join all positive plate lugs in the book. The battery plate book, now with straps connected, is placed into the battery case.
As the process for producing batteries is so lengthy and complex, and the present methodology for detecting electrical shorts occurs only after the battery has been substantially assembled, a need exists to eliminate the source of electrical shorts altogether. The present invention provides an improved battery plate stacker including a wire flattener module that substantially eliminates the occurrence of electrical shorts resulting from piercing the separator material with exposed wires from the expanded metal battery plate wire grid.
One embodiment of the present invention includes a battery plate stacker for enveloping expanded metal plates and stacking positive and negative plates in an alternating pattern, comprising, a battery plate feeder, a carrier coupled to the battery plate feeder, and a wire flattener module coupled to the carrier conveying the expanded metal plates through the wire flattener module. The inclusion of the wire flattener module in the battery plate stacker presents a major advance over the art, since it reduces the incidence of separator damage from wires along the edge of the expanded metal plates that extend away from the plate""s surface. By reducing the occurrences of separator damage from extended wires, the present invention reduces the average time required to produce a number of properly operating batteries, and increases the overall quality of the batteries.
The carrier comprises a pair of driven chains, wherein each chain has at least one dog aligned with a corresponding dog on the other chain for engagement with an edge of an expanded metal plate.
The wire flattener module comprises a pair of members having a gap in between, and a portion located near an edge of each expanded metal plate passes through the gap. Preferably, the gap is less than or equal to the minimum thickness of the portion located near the edge for each expanded metal plate. Setting the gap distance to the minimum plate width, or smaller, one ensures the ability to handle expanded metal plates of larger widths. For example, if a manufacturers"" minimum expanded metal plate width was 0.040xe2x80x3 then a gap width of 0.040xe2x80x3 (or smaller) makes sense because it enables handling plates with larger widths, thereby creating system flexibility.
The pair of members preferably comprises a first disk and a second disk. Typically, the first and second disks are coplanar. Additionally, the first and second disks are rotatable about their respective axes, and one of the disks is spring-loaded toward the other disk. The first and second disks are located below and above, respectively, the expanded metal plate when it lies flat on the carrier. Moreover, a top surface of the first disk is located at a height substantially equal to the bottom surface of the expanded metal plate when it lies flat on the carrier.
Alternatively, one could define the pair of members of the wire flattener module in more general terms. For example, one member of the pair of members has a smooth, circumferential surface that is driven to make forcible, downward contact along an upper surface portion proximate the plates"" edge when the expanded metal plate, while lying flat, is moved by the carrier through the gap. Similarly, the other member of the pair of members has a smooth, circumferential surface that makes forcible, upward contact along a lower surface portion proximate the plates"" edge when the expanded metal plate, while lying flat, is moved by the carrier through the gap.
The wire flattener assembly further comprises a second pair of members having a second gap in between and through which another portion located near the opposite edge of each expanded metal plate passes. The second pair of members are substantially identical to those described above, so their details will not be repeated here. Nevertheless, note that addition of the second pair of members permits simultaneous wire flattening on opposing edges of each expanded metal plate. Without two pairs of such members, one envisions plates requiring wire flattening on only one edge, or if more than one edge needs wire flattening, then more than one pass through the single pair of members.
In another embodiment of the present invention, a method of processing expanded metal battery plates is disclosed comprising the steps of providing an expanded metal battery plate ready for envelopment in separator material, and having at least one edge with an exposed wire grid; applying force simultaneously on an upper and a lower surface in proximity to each edge with the exposed wire grid; and enveloping the expanded metal battery plate. The force is sufficient to move wires from the exposed wire grid that extend away from the upper and lower surfaces to positions substantially flush with the surfaces, without damaging the expanded metal battery plate. Sufficient force, as defined above, is established in large part by setting an appropriate gap (as mentioned with respect to the first embodiment disclosed above), and other design factors such as proper spring selection.
These and other objects, advantages, and aspects of the invention will become apparent from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention and reference is made therefor, to the claims herein for interpreting the scope of the invention.